1. Field of the Invention
The present invention relates to an improvement of binding tool of friction welding type for a thermoplastic strap, wherein the thermoplastic strap wound and overlapped about an article is tightened, an overlapped part of strap tightened is frictionally welded by vibrating an upper strap, while applying pressure to the overlapped strap part by an vibrator, and the succeeding excess part of upper strap in the overlapped strap part that is frictionally welded is cut off.
2. Description of the Prior Art
Conventionally, binding of articles by using a thermoplastic strap has been widely performed. Particularly in these days, the thermoplastic straps have been significantly increased in tensile strength, and widely applied even for heavy articles. In such tendency, the technology for welding an overlapped part of thermoplastic strap has been significantly advanced, and a lot of binding machines and tools of friction welding type are found. Specifically, a small and heavy-duty binding tool of friction welding type that needs no bulky facility and structure, and is carried at any time to an appropriate place for binding operation is on demand.
Key requirements for such binding tool of friction welding type are that pressure and vibration by a vibrator should be efficiently and faultlessly transmitted to the overlapped strap part, and the structure should be simplified to provide as small size and as light weight as possible. However, conventional tools are not always satisfactory. In other words, the efficiency of pressurization and vibration has been unachieved, when compactness and weight reduction are importantly addressed to, and a slight bulkiness has been unavoidable, when the efficiency of pressurization and vibration is put into focus. For example, such a binding tool as described in Japanese Patent KOKOKU No. 42-19238 and No. 2-10006 is complicated in structure, and has a problem even in terms of the efficiency of pressurization and vibration, because the overlapped strap part is vibrated arcuately.
In addition, although a cutting device shown in Japanese Patent KOKOKU No. 2-10006 is relatively convenient, because it is adapted to utilize a high-speed vibration in the direction of width for friction welding of the overlapped strap part, and cut the succeeding excess part of upper strap of the overlapped part only by slightly applying pressure with a cutting blade, increase of the manufacturing cost has been unavoidable. Moreover, since the overlapped strap part is vibrated arcuately, the cutting blade is also arranged so as to be moved along an arcuate track, and it has not always been satisfiable even in terms of cutting efficiency.